1. Field of the Invention
The field generally relates to connecting graft tubes to vessels after entering the vasculature through a skin puncture. Specifically the present device provides a means by which short sutures in a circular cuff on each end of a graft tube use stored energy to curve through tissue of an adjacent lumen wall from inside the graft tube thus connecting it to the lumen wall in which it is concentrically located with the object of providing a conduit for blood to flow inside, rather than outside a diseased vessel that has become so occluded it can no longer perform its function. The device can also provide a scaffold for growing living linings inside the vessel or function as a dialysis shunt.
2. Prior Art
Prior Art References:
US Patent Number,Year,Name3,334,6291967 Aug. 08Cohn3,494,0061970 Feb. 10Brumlik4,503,5691985 Mar. 12Dotter4,733,6651988 Mar. 29Palmaz4,893,6231990 Jan. 16Rosenbluth5,002,5631991 Mar. 26Pyka5,197,9781992 Mar. 30Hess5,163,9551992 Nov. 17McNamara5,662,7001997 Aug. 02Lazarus5,810,8701998 Sep. 22Myers6,652,5702003 Nov. 25Smith6,264,6842001 Apr. 24Banas7,713,2152010 May 11Shriver7,771,4222010 Aug. 10Shriver
Atherosclerosis is a disease that afflicts about 20 million people in the United States; more than any other life threatening disease. The Greek word “athero” means “gruel” and “sclerosis” “hardening,” so the disease is also known as “hardening of the arteries.” Today this gruel is often called “plaque,” and may produce fatty deposits, hard calcium deposits, or interact with clotted blood in producing aneurysms. Regardless of the nature of the occlusion, its effect is to occlude the artery making it incapable of performing its function of delivering oxygen-carrying blood to muscles and organs beyond the occlusion. When the brain or heart is oxygen-deprived, death or impairment occurs rapidly. When muscles of the lower body are oxygen-deprived, death is slower but half die within 10 years. There may or may not be pain symptoms in the legs and gangrene may be the first clear indication. Amputation is often required to avoid death. Atherosclerosis may be treated by diet and drugs but patients often do not follow diets and the effects of tobacco smoke are irreversible even if the person stops smoking.
The gold standard treatment is a bypass graft with its ends “grafted” to the artery on each side of the occlusion thus carrying blood around it. A bypass graft remains functional about 7½ years on average. Despite being the “gold standard,” the problem with bypass grafts is they require surgery to place them in the body. Surgery is risky and debilitating. For instance, a coronary bypass procedure starts with splitting the sternum and pulling apart the rib cage in what was called the “bloody eagle” torture in earlier centuries. This is just to allow the surgeon's hands to get in the body to suture one or more bypass grafts around occlusions. There are so-called “Da Vinci” machines that assist the surgeon's fingers in remaining steady enough to place coronary bypasses through openings in the chest, but this machine is applicable in a limited number of circumstances. Open surgery to place a bypass graft in the lower body is not quite as debilitating as that for opening the chest but is risky and involves a long recovery time in comparison to percutaneous entry through a skin puncture. The catheter-based methods of entering the body through a skin puncture go through the occlusion rather than going around it. A balloon is inflated in the occlusion to open it, but the occlusion starts to close (restenosis) when the balloon is removed. To keep the occlusion propped open, stents were developed in the 1990s. Stents are wire mesh tubes that increase the length of time balloon treatments last in coronary artery applications. But in the longer arteries and occlusions of the legs stents do not improve the duration of a balloon treatment. Occlusions grow back through openings in the wire mesh and stents tend to fracture in the dynamic leg environment. Thus the duration of balloon and stent treatments in the legs is about 2½ years on average. Bypass grafts last about 7½ years on average, or about 3 times the duration of balloons with or without stents. Balloon treatments have largely replaced bypass graft treatment as surgery now required to place bypass grafts is a last resort after many balloon failures, so used in only about 20% of the peripheral artery cases. The problem of the occlusion growing back through the open mesh in stents was dealt with in 2005 by placing a substance on the stent to resist that growth. But the drug has created other problems, like causing blood clots that sometimes get caught in an artery to the brain and cause a stroke from loss of blood to the brain. The latest “fix” for stents is placing graft tubes on them in so-called stent grafts thus closing open holes in the mesh and sealing off the diseased tissue. These stent grafts have included ePTFE and heparin bioactive surfaces to inhibit intimal hyperplasia and regrowth of the occlusion. But occlusions tend grow back at the ends of stent grafts. Whether the addition of a graft to the stent will avoid the problems of the stent fracturing in the dynamic environment of the legs has not yet been determined nor has the duration of this treatment. The stent graft includes metal so is not biodegradable and thus not useful in combination with tissue engineered vessels (TEV) that are graft tubes made from the patient's own body cells. The TEVs duplicate the structure of the artery wall's three layers, including those of muscle and elasticity and vascular endothelial growth factors are used with these TEVs. But as long as surgery is needed to place them in the body, their use will be limited to a fraction of the 20% of cases treated by surgery. There are catheter-based devices other than balloons, stents and stent grafts for opening occlusions. They utilize grinding, freezing, jetting fluid, lasering, etc., to remove the various types of deposits after entering through a skin puncture. They are generally effective in removing the occlusion but the occlusions grow back just as fast as when treated with balloon angioplasty. So these removal devices do not appear to increase the duration of balloons with or without stents. However they may be used in combination with a device for placing a bypass graft through a skin puncture. Data from peer-reviewed articles may be summarized as: bypass grafts, whether artificial or a vein from the patient's own body, last about 50% longer than balloons and stents in the short coronary arteries and about 300% longer in the peripheral arteries of the lower body. Restenosis, or regrowth of the occlusion, is faster in longer occlusions of the legs. Also stents tend to fracture in the dynamic environment of the legs. Stents that elute drugs to prevent regrowth of occlusions through openings in the mesh create problems such as blood clots. Closing the mesh opening by combining a graft tube with a stent causes the occlusions to regrow around the ends of the stent grafts and does not solve the problem of metal stents fracturing in the legs. Thus, though the percutaneous methods lack the effectiveness of the bypass graft, skin punctures are so much safer and less debilitating than open surgery that balloons and stents have become the preferred treatment for coronary and peripheral arteries. If the safety of skin punctures can be combined with the effectiveness of bypass grafts in a new device and procedure, it would likely replace many of the other means of treating hardening of the arteries.
Two patents have been issued to the present inventor for devices that place bypass grafts around the occlusion in both coronary and peripheral arteries. There also appears to be a need for a device that provides the means of placing a graft tube inside the vasculature after the occlusion is removed, perhaps providing a more effective or safer treatment than a bypass graft around the occlusion. Furthermore it would be usable in combination with, and provide a scaffold for placing TEVs inside the vasculature and biodegrading as the TEV grows into the lumen wall. To accomplish these objects, the graft tube must avoid the means used by stents to attach to lumen walls, namely by pressure exerted throughout their length, and should be capable of accomplishing the object when constructed entirely of biodegradable material.
These objects are not accomplished by balloons, stents, eluting stents, and stent grafts, alone or combined.
The present device will suture a graft tube inside the artery after the occlusion is removed. Specifically, the graft tube is not a stent or stent graft. A stent graft combines stent and graft tube that connects to the lumen wall by the pressure exerted by the metal stent throughout the length of the stent graft. Patents for stents and for stent grafts are cited as prior art, but none attach to the lumen wall by sutures. All attach by exerting pressure from the expanding stent against lumen walls. Therefore there is only the object of stents that could be considered prior art but no stent graft use the means of attaching to lumen wall by sutures. It does not require a detailed analysis of each patent to show how the basic means of attachment by stents is different from the means of attachment by sutures but examples of stent patents are included.
The only prior patent found using a means other than stents to attach a graft tube to a lumen wall from inside the lumen is the Lazarus patent 5,662,700 in which he describes an artificial graft and implantation method where a prosthesis graft is placed inside a blood vessel which may be an artery. He refers to aneurysms as weakened blood vessels creating a need for prosthesis such as an artificial vessel or graft. The device is described as having one or more staples (sharp hooks) attached to each end of the intraluminal graft to prevent it from migrating. Thus the objective is the same as that of the present invention, namely to connect the ends of a graft tube to the lumen wall in which it is concentrically located without using a stent. Lazarus utilizes hooks pushed into the lumen wall on the ends of a graft tube rather than along its entire length to hold it in place. He cites prior devices that used hooks as the means of attaching one surface to another. Since Lazarus does not mention any means for removing or pushing aside occlusions such as fatty material, blood clots or calcified material in order for the device to be put in place, it may be assumed his device is intended for coronary artery applications as his device might be able to push aside some short coronary occlusions but not the long occlusions typically found in the long peripheral arteries of the legs. Also, the means of attaching by hooks may be tolerable in coronary arteries as they are surrounded by pericardial fluid whereas peripheral arteries are surrounded by muscle tissue, nerve and vein which could be injured by hooks moving outside the lumen wall. The hooks will prevent the graft tube from moving in the direction the hooks are pointed but not in the direction the points of the hooks are pointed unless the graft tube is stretched tautly between hooks.
Cohn, in 3,334,629 describes a means of attaching a device inside a blood vessel in which extensible vanes having sharp teeth on the ends engage the interior walls of a blood vessel for the object of keeping it fixed in place. This has similarities to the Lazarus device in the use of hooks but not to the proposed device.
Brumilik, in patent 3,494,006 describes a fastening device intended as an improvement over a “velcro” type fastener in that only one surface is provided with fastener means, the other being permanently attached to elongated bodies having at least one barb on the free end which is intended to penetrate and lodge in the article to which adhesion is desired. This is not the means proposed with the present device, namely using sutures for the connection.
Prior devices by the present inventor are for placing a bypass graft around the occlusion as done in open surgery and not for placing the graft through the occlusion concentrically inside the diseased vessel. In patent 7,771,442 a combination seal and suture is described where stiff sutures are located in hollow sutures in the longitudinal portion of a seal attached to the end of a bypass graft. An inflatable balloon with push rods on its circumference is used to push the sutures out of the longitudinal section of the seal as the flange on its end is held by a holding balloon. The sutures are driven through the artery wall and into the flange located inside the artery lumen. The stiff sutures move forward in the direction they are pointed by the hollow sutures in which they are located. There is no tunnel in the flange for the stiff suture to enter, though there may be a trench to hold the stiff suture while it punctures a tunnel. This method attaches the seal (and the graft tube with a seal on each end) to the artery in fluid-tight connections on each side of the occlusion.
That invention requires another invention by Shriver, 7,713,215, which describes a device for piercing and dilating tissue to make an opening in the side of the artery for the seal flange to enter the lumen of the artery and dilate a tunnel outside the artery in which to place the graft. The flange is pushed through this opening in the side of the artery to expand inside the artery lumen and thus fit against the lumen wall to receive the stiff sutures pushed from the stem section of the seal after they pass through the tissue on the edge of the opening in the side of the artery.
The present invention utilizes a circular cuff rather than a seal and the cuff is entirely inside the artery rather than half in/half out of the artery as are the stem and flange portions of the seal. The present invention does not require an opening in the side of the artery because the graft tube, with circular cuffs on each end, is concentrically within the artery lumen. Short sutures, manufactured in a particular configuration are forced into a tunnel in the circular cuff thus storing energy in them prior to their use. They are pushed out of the tunnel and the stored energy is released causing the short suture to curve through tissue in the lumen wall and return to the circular cuff. The circular cuff has a second tunnel for the short sutures to enter and lodge in. The sutures hold both ends of the graft tube in place in the artery lumen, thus providing a conduit of biodegradable or non-biodegradable material lining the diseased section of artery or vein. The occlusion is removed by one of the standard devices for that purpose before the graft tube is placed.